In an electrophotographic image forming apparatus or electrostatic recording apparatus, an electric or magnetic latent image has been developed with a toner. For example, in an electrophotography, an electrostatic charge image (latent image) has formed on a photoconductor and then developed with a toner to thereby form a toner image. The toner image is usually transferred onto a recording medium such as paper and then fixed with, for example, heating.
In an image forming method using a heat-fixing system in which a toner is fixed with heating, a large amount of electric power is required in a process in which a toner is heat-melted to be fixed onto a recording medium such as paper. Therefore, one of important properties of a toner is low temperature fixability in terms of energy-saving.
In order to improve low temperature fixability of a toner, it is important to control thermal property of a binder resin which is major component of the toner.
Therefore, there has been suggested to, in a toner in which a crystalline resin is a major component of a binder resin, control a composition and thermal property of the crystalline resin so as to fall within a certain range (see, for example, PTL 1).
There also has been suggested to use a toner which contains, as a binder resin, two crystalline resins having different molecular weights under a certain fixing condition (see, for example, PTL 2).
There also has been suggested a toner which contains, as a binder resin, two crystalline polyester resins having different storage elastic moduli at 160° C. (see, for example, PTL 3).
In the case where a toner containing a crystalline resin is used, although it is excellent in low temperature fixability, the following problem will more likely occur compared to the case where a toner containing a non-crystalline resin as a major component of a binder resin is used. That is, when printing on paper having a wider width in a direction orthogonal to a conveyance direction of a sheet-shaped medium (e.g., A3 size paper) after continuously printing on sheets of paper having a narrower width (e.g., A4 size paper), there will occur problems such as toner offset on parts of a surface of a fixing member corresponding to ends of the paper having a wider width (hereinafter may be referred to as “end-offset”) and gloss unevenness at ends of the paper having a wider width, resulting from a difference of their paper-feeding sizes.
Therefore, there has been a need for providing a toner being capable of preventing end-offset and gloss unevenness even in the case of containing a crystalline resin.